Microchemical systems are systems for carrying out highly sensitive detection or analysis on a very small amount of a sample using a capillary tube or a fluorescence analysis chip. For example, a fluorescence analysis chip has provided therein a very fine channel through which a solution containing a very small amount of a sample (a sample solution) flows. The channel may have any of various forms, for example a branching channel or a merging channel, or a meandering channel.
As methods for highly sensitive detection as described above, photothermal conversion spectroscopic analysis and laser induced fluorescence (LIF) analysis have been known from hitherto. LIF analysis is a method in which targeted fluorescent molecules are subjected to electron excitation by a laser, and fluorescence emitted when the excited electrons drop back down to the ground state is measured. A resonant transition between energy levels is used, and hence the probability of excitation is high, and thus detection is possible with very high sensitivity.
For example, as prior art, there has been disclosed a system in which exciting light is convergently irradiated onto a sample flowing through a very fine channel formed in a small glass substrate or the like via a lens from a bottom surface of the channel, and fluorescence thus emitted by the sample is detected from a side of the channel (see, for example, Japanese Laid-open Patent Publication (Kokai) No. 2002-214194).
A problem of such a microchemical system according to the prior art is that the optical systems and so on for light sources, a measurement section and a detection section (photoelectric conversion section) have a complex construction, and hence the system is large in size and lacking in portability, and thus there are limitations with regard to the installation site and the operation of the apparatus, resulting in the work efficiency for users being poor. As prior art solving this problem, there has been disclosed a microchemical system in which exciting light is convergently irradiated onto a sample flowing through a channel formed in a small glass substrate or the like via a lens from an upper surface of the channel, and fluorescence thus emitted by the sample is led to a detector by a lens in the upper surface of the channel, whereby the microchemical system when configured for carrying out LIF analysis can be made compact in size overall (see, for example, Japanese Laid-open Patent Publication (Kokai) No. 2002-131280).
However, in the prior art described above, the exciting light is led to a lens, and the fluorescence is led out via the lens, and hence a dichroic mirror must be disposed in the microchemical system inclined at 45° to the optical axis of the exciting light. Due to differences in wavelength characteristics between P polarized light and S polarized light, the boundary between a reflected wavelength band and a transmitted wavelength band is broadened, and hence of light outputted from the sample, light other than the fluorescence may enter the detector, resulting in it not being possible to carry out LIF analysis accurately.
Moreover, the sample flowing through the channel emits fluorescence isotropically, and hence in the case of carrying out LIF analysis using a system constructed as described above, only the fluorescence emitted toward the detector can be detected. There has thus been a limit on the ability to carry out analysis and identification of substances that emit fluorescence weakly.
Moreover, there have been no microchemical systems capable of carrying out both LIF analysis as described above and photothermal conversion spectroscopic analysis, and hence there has been the problem of it being necessary to provide separate systems for each.
It is an object of the present invention to provide a fluorescence analysis optical multiplexer/demultiplexer, a fluorescence analysis optical module, a fluorescence analyzer, a fluorescence/photothermal conversion spectroscopic analyzer, and a fluorescence analysis chip, according to which LIF analysis can be carried out easily and with high sensitivity, and moreover photothermal conversion spectroscopic analysis can be carried out easily and simultaneously with the LIF analysis.